Apparatus for perforating running webs of wrapping material and cleaning devices therefor

Abstract

Apparatus for perforating a running web of wrapping material, such as a web of tipping paper in a filter tipping machine for the making of filter cigarettes, is advanced through two successive electric perforating units one of which is active while the other is idle, and vice versa. This renders it possible to clean the perforating electrodes of the idle unit while the electrodes of the active unit produce sparks which remove fragments of material from the web to form one or more rows of perforations and to thus influence the permeability of the web. The apparatus can be installed in a filter tipping machine between a reel for a supply of convoluted web of tipping paper and a severing device which subdivides the leader of the perforated web into uniting bands serving to connect pairs of plain cigarettes with filter mouthpieces of double unit length.

We claim: 
     
       1. Apparatus for electrically perforating a running web of wrapping material for smokers' products, comprising means for advancing a web in a predetermined direction along a predetermined path; a first perforating unit adjacent a first portion of said path; and a second perforating unit adjacent a second portion of said path downstream of said first portion, each of said units comprising first and second electrode holders disposed at opposite sides of said path and at least one row of perforating electrodes on each of said holders, said rows extending substantially in said predetermined direction and each electrode on each of said first holders being located opposite an electrode on the respective second holder, the distribution of electrodes in said first unit with reference to said path being substantially identical with the distribution of electrodes in said second unit with reference to said path so that one of said units can be operated to perforate the running web while the other of said units is idle without altering the perforating action upon the web. 
     
     
       2. The apparatus of claim 1, further comprising means for cleaning portions of said units. 
     
     
       3. The apparatus of claim 1, and further comprising means for selectively connecting the electrodes of said first and second units with an energy source independently of each other. 
     
     
       4. The apparatus of claim 3, further comprising a first cleaning device for the electrodes of said first unit and a second cleaning device for the electrodes of said second unit. 
     
     
       5. The apparatus of claim 1, further comprising means for opening and closing each of said units independently of each other. 
     
     
       6. The apparatus of claim 1, further comprising first and second cleaning devices for portions of said first and second units, respectively, each of said devices comprising at least one rotary brush. 
     
     
       7. The apparatus of claim 6, wherein each of said devices comprises a plurality of brushes. 
     
     
       8. The apparatus of claim 1, further comprising means for converting the perforated web into uniting bands for use in a filter tipping machine downstream of the second portion of said path. 
     
     
       9. The apparatus of claim 1, wherein said first and second units further comprise first and second means for respectively supplying to the electrodes of said first and second units high-voltage impulses at a predetermined frequency. 
     
     
       10. The apparatus of claim 9, further comprising means for connecting said supplying means with and for disconnecting said supplying means from the respective sets of electrodes independently of each other, including means for connecting said second supplying means with the second set of electrodes with a predetermined delay following disconnection of said first supplying means from the first set of electrodes. 
     
     
       11. The apparatus of claim 9, further comprising means for connecting said supplying means with and for disconnecting said supplying means from the respective sets of electrodes independently of each other, including means for disconnecting said second supplying means from the second set of electrodes with a predetermined delay following connection of said first supplying means with said first set of electrodes. 
     
     
       12. The apparatus of claim 1, further comprising a source of convoluted web upstream of said first portion and a web severing device downstream of said second portion of said path. 
     
     
       13. Apparatus for electrically perforating a running web of wrapping material for smokers' products, comprising means for advancing a web in a predetermined direction along a predetermined path; a first perforating unit adjacent a first portion of said path; a second perforating unit adjacent a second portion of said path downstream of said first portion, each of said units comprising first and second electrode holders disposed at opposite sides of said path; and means for opening and closing each of said units independently of each other, including means for moving said first holders between retracted positions more distant from and extended positions nearer to the respective second holders. 
     
     
       14. The apparatus of claim 13, further comprising perforating electrodes provided on said holders, and means for cleaning said electrodes including a first cleaning device for the electrodes on the holders of said first unit, a second cleaning device for the electrodes on the holders of said second unit, and means for moving said devices relative to and between the respective holders in the retracted positions of the respective first holders. 
     
     
       15. Apparatus for electrically perforating a running web of wrapping material for smokers' products, comprising means for advancing a web in a predetermined direction along a predetermined path; a first perforating unit adjacent a first portion of said path; a second perforating unit adjacent a second portion of said path downstream of said first portion, each of said units comprising a plurality of perforating electrodes; and means for cleaning said electrodes including first and second mechanical cleaning devices for the electrodes of said first and second units, respectively, and first and second pneumatic cleaning device for the electrodes of said first and second units, respectively. 
     
     
       16. The apparatus of claim 15, wherein said pneumatic cleaning devices include vacuum cleaners. 
     
     
       17. The apparatus of claim 15, wherein said pneumatic cleaning devices include means for blowing a pressurized fluid against the respective electrodes.